Perhaps this is old news, but I made a discovery today while sanding, sanding, and more sanding on my boat project. I was looking at the pile of spent 5" sanding discs, lamenting the fact that there was plenty of life in the middle; only the edges really wear out. Then it dawned on me. I stuck one on my oscillating multi-tool attachment, and trimmed it to fit the triangular shape. Et voila! Another whole use cycle. The multi-tool gets into much tighter spots, which there are a LOT of on a lapstrake boat. I even have a tiny detail sander that goes on it, and could probably trim spent multi-tool sanding pads to fit it. I know that this wouldn't make sense for a commercial operation, but for the impecunious backyard builder, you might save a few coppers. Hint- don't use your wife's fancy dress-makers shears to cut sanding discs...